Lithium-supplementing process method for lithium iron phosphate positive electrode and use thereof

Abstract

The present application relates to a lithium-supplementing process method for a lithium iron phosphate positive electrode, and a use thereof. The process method comprises the following steps: (1) mixing lithium iron phosphate and a lithium-supplementing agent, and performing first stirring to obtain a main powder; (2) mixing a first conductive agent, a binder, a dispersing agent, a solvent and the obtained main powder, and performing second stirring to obtain a mixture; and (3) mixing a second conductive agent and the obtained mixture, and performing third stirring to obtain a positive electrode slurry.

Description

A process for replenishing lithium in a lithium iron phosphate cathode and its application

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on September 27, 2023, with application number 202311263064.6. The entire contents of the above application are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of lithium-ion battery positive electrodes, and in particular to a process method for replenishing lithium in lithium iron phosphate positive electrodes and its application. Background Art

[0003] Lithium-ion batteries are widely used in digital electronics, power tools, electric vehicles, energy storage, and other fields. Consumers are currently placing higher demands on their high energy density and high power density. Silicon has a higher capacity than the currently commercially used graphite anode material, and its use as an anode material significantly improves the energy density of lithium-ion batteries. However, the commercial application of silicon-based materials is severely restricted by their low initial coulombic efficiency and 300% volume expansion. Pre-lithiation can compensate for the irreversible lithium consumption caused by the SEI formed in the silicon material during the initial charge of the full battery, thereby improving the battery's energy density.

[0004] Currently, common lithium replenishment technologies are divided into two categories: positive electrode replenishment and negative electrode replenishment. In terms of negative electrode replenishment, for example, related art discloses a method for lithium plating on the negative electrode sheet of a lithium-ion battery. The negative electrode sheet is plated with lithium using a vacuum coating method (under inert gas protection conditions) to form a lithium-plated layer on the surface of the negative electrode sheet. However, due to the high activity of metallic lithium powder or lithium foil, safety control is difficult and the lithium replenishment effect is poor. Therefore, it is very necessary to develop a lithium replenishment method that is both safe, simple, and effective.

[0005] Compared to negative electrode lithium replenishment, positive electrode lithium replenishment offers greater safety, operability, and equipment compatibility. The method of using positive electrode lithium replenishment additives, which involves mixing high-lithium-containing, low-reversible-capacity positive electrode active materials with conventional positive electrode active materials in a specific ratio and using them as a new positive electrode active material for battery assembly, is becoming a research hotspot.

[0006] Related technologies disclose a positive electrode lithium replenishment slurry, preparation method, and application thereof, for lithium-ion batteries. The positive electrode lithium replenishment slurry comprises a lithium replenishment material, a dispersant, a conductive additive, and a solvent. The lithium replenishment material is lithium oxide, and the mass percentage of the lithium replenishment material is 1 to 90 wt% of the lithium replenishment slurry. The lithium replenishment slurry provided by this patent has a simple preparation process. After adding the dispersant, it is not easy to agglomerate to form secondary large particles, which can significantly reduce the particle size. The positive electrode lithium replenishment additive in the slurry can effectively decompose to replenish the lithium ions lost due to the formation of the SEI film during discharge, thereby ensuring that more lithium ions can be re-embedded in the positive electrode material, improving the capacity of the positive electrode material and ultimately increasing the energy density of the lithium-ion battery.

[0007] Related technology discloses a lithium-ion battery and a method for replenishing lithium in the positive electrode thereof, belonging to the field of lithium-ion batteries. The method for replenishing lithium in the positive electrode of a lithium-ion battery includes: using a lithium replenishing composition in the lithium-ion battery and adding an additive to the electrolyte of the lithium-ion battery. The lithium replenishing composition includes a lithium replenishing material and a reducing agent. The lithium replenishing material includes one or more of lithium orthosilicate and lithium metasilicate; the reducing agent includes one or more of elemental sulfur, elemental phosphorus, elemental boron, molybdenum sulfide, tungsten sulfide, titanium sulfide, lithium sulfide, magnesium sulfide, calcium sulfide, lanthanum sulfide, tantalum sulfide, and iron sulfide; and the additive includes one or more of lithium bis(oxalatoborate), lithium difluorooxalatoborate, 1,3-propane sultone, and fluoroether. This lithium replenishing method can effectively improve the energy density and cycle life of lithium-ion batteries.

[0008] Currently, the cathode lithium replenishment process typically involves mixing cathode lithium replenishment materials with cathode powder to form a mixed colloid before subsequent coating. This often results in a rapid increase in the viscosity of the subsequent slurry after discharge due to uncertain addition order, making subsequent coating difficult. Improving the cathode lithium replenishment process and enhancing battery performance is a pressing technical challenge. Technical issues

[0009] The present application provides a process for replenishing lithium in a lithium iron phosphate positive electrode and its application to solve the above technical problems. Technical Solutions

[0010] In a first aspect, the present application provides a process for replenishing lithium in a lithium iron phosphate positive electrode, the process comprising the following steps:

[0011] Mixing lithium iron phosphate and a lithium supplement agent, performing a first stirring, and obtaining a main powder;

[0012] mixing a first conductive agent, a binder, a dispersant, a solvent and the obtained main powder, and performing a second stirring to obtain the mixed material;

[0013] The second conductive agent and the obtained mixture are mixed and a third stirring is performed to obtain a positive electrode slurry, thereby completing the process method for replenishing lithium of a lithium iron phosphate positive electrode.

[0014] In a second aspect, the present application provides a positive electrode slurry, which is obtained using the process method described in the first aspect.

[0015] In a third aspect, the present application provides a positive electrode sheet, wherein the positive electrode sheet contains the positive electrode slurry as described in the second aspect.

[0016] In a fourth aspect, the present application provides a battery, wherein the battery contains the positive electrode sheet as described in the third aspect. Beneficial effects

[0017] The beneficial effects of the present application are as follows: in the first step, the present application mixes the positive electrode lithium supplement and the lithium iron phosphate material into a main powder, so that the lithium supplement is fully uniform in the main powder system, and then the main powder is mixed with the remaining materials to form a positive electrode slurry, thereby ensuring the stability of the discharge, solving the problem of excessive viscosity increase during the slurry preparation process, and improving the performance of the battery cell. Among them, the electrode surface density can reach more than 192g / ㎡, and the thickness can be as low as less than 169.3mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG1 is a flow chart of a process for replenishing lithium in a lithium iron phosphate positive electrode according to the present application. Modes for Carrying Out the Invention

[0019] In order to solve the above technical problems, the present application provides a process method for replenishing lithium in a lithium iron phosphate positive electrode and its application. In the first step, the present application mixes the positive electrode lithium replenisher and the lithium iron phosphate material into a main powder, so that the lithium replenisher is fully uniform in the main powder system, and then the main powder is mixed with the remaining materials to form a positive electrode slurry, thereby ensuring the stability of the output, solving the problem of rapid viscosity increase during the slurry preparation process, and improving the performance of the battery cell.

[0020] As shown in FIG1 , according to one aspect of the present application, a process for replenishing lithium in a lithium iron phosphate positive electrode is provided, the process comprising the following steps:

[0021] (1) Mixing lithium iron phosphate and lithium supplement agent, performing a first stirring to obtain a main powder;

[0022] (2) mixing the first conductive agent, the binder, the dispersant, the solvent and the obtained main powder, and performing a second stirring to obtain the mixed material;

[0023] (3) The second conductive agent and the obtained mixture are mixed and a third stirring is performed to obtain a positive electrode slurry, thereby completing the process method for replenishing lithium iron phosphate positive electrodes.

[0024] In the first step, the present application mixes the positive electrode lithium supplement and lithium iron phosphate material into a main powder, so that the lithium supplement is fully uniform in the main powder system, and then the main powder is mixed with the remaining materials to form a positive electrode slurry, thereby ensuring the stability of the output, solving the problem of rapid viscosity increase during the slurry preparation process, and improving the performance of the battery cell.

[0025] In some embodiments, the lithium supplement in step (1) includes Li5FeO4.

[0026] In some embodiments, the mass of the lithium iron phosphate in step (1) is 95-96% of the mass of the positive electrode slurry, wherein the mass fraction can be 95%, 95.1%, 95.2%, 95.3%, 95.4%, 95.5%, 95.6%, 95.7%, 95.8%, 95.9% or 96%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] In some embodiments, the mass of the lithium supplement agent in step (1) is 1-3% of the mass of the positive electrode slurry, wherein the mass fraction can be 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8% or 3%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] In some embodiments, the revolution speed of the first stirring in step (1) is 15~25r / min, wherein the speed can be 15r / min, 16r / min, 17r / min, 18r / min, 19r / min, 20r / min, 21r / min, 22r / min, 23r / min, 24r / min or 25r / min, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] In some embodiments, the dispersion speed of the first stirring in step (1) is 180~220r / min, wherein the dispersion speed can be 180r / min, 185r / min, 190r / min, 195r / min, 200r / min, 205r / min, 210r / min, 215r / min or 220r / min, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] In some embodiments, the first stirring time in step (1) is 10 to 30 minutes, wherein the time can be 10 minutes, 12 minutes, 14 minutes, 16 minutes, 18 minutes, 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes or 30 minutes, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] In some embodiments, the mass of the first conductive agent in step (2) is 0.1-0.6% of the mass of the positive electrode slurry, wherein the mass fraction can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5% or 0.6%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] In some embodiments, the first conductive agent in step (2) includes conductive carbon black.

[0033] In some embodiments, the solvent in step (2) comprises N-methylpyrrolidone.

[0034] In some embodiments, the binder in step (2) includes polyvinylidene fluoride.

[0035] In some embodiments, the mass of the binder in step (2) is 0.2-0.8% of the mass of the positive electrode slurry, wherein the mass fraction can be 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7% or 0.8%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] In some embodiments, the dispersant in step (2) comprises polyvinyl pyrrolidone.

[0037] In some embodiments, the mass of the dispersant in step (2) is 0.1-0.5% of the mass of the positive electrode slurry, wherein the mass fraction can be 0.1%, 0.2%, 0.3%, 0.4% or 0.5%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] In some embodiments, the revolution speed of the second stirring in step (2) is 10~20r / min, wherein the revolution speed can be 10r / min, 11r / min, 12r / min, 13r / min, 14r / min, 15r / min, 16r / min, 17r / min, 18r / min, 19r / min or 20r / min, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] In some embodiments, the dispersion speed of the second stirring in step (2) is 180~220r / min, wherein the dispersion speed can be 180r / min, 190r / min, 200r / min, 210r / min or 220r / min, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] In some embodiments, the second stirring time in step (2) is 5 to 15 minutes, wherein the time can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes or 15 minutes, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] In some embodiments, the second conductive agent in step (3) comprises carbon nanotubes.

[0042] In some embodiments, the mass of the second conductive agent in step (3) is 0.2-0.7% of the mass of the positive electrode slurry, wherein the mass fraction can be 0.2%, 0.3%, 0.4%, 0.5%, 0.6% or 0.7%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] In some embodiments, the revolution speed of the third stirring in step (3) is 15~25r / min, wherein the revolution speed can be 15r / min, 16r / min, 17r / min, 18r / min, 19r / min, 20r / min, 21r / min, 22r / min, 23r / min, 24r / min or 25r / min, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0044] In some embodiments, the third stirring time in step (3) is 100-140 min, wherein the time can be 100 min, 105 min, 110 min, 115 min, 120 min, 125 min, 130 min, 135 min or 140 min, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0045] In some embodiments, the viscosity of the mixture in step (2) is 12,000 to 14,000 MPa·s, for example, 12,000 MPa·s, 12,500 MPa·s, 13,000 MPa·s, 13,500 MPa·s or 14,000 MPa·s, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0046] In some embodiments, the solid content of the mixture in step (2) is 71-72%, wherein the solid content can be 71%, 71.1%, 71.2%, 71.3%, 71.4%, 71.5%, 71.6%, 71.7%, 71.8%, 71.9% or 72%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0047] In some embodiments, the viscosity of the positive electrode slurry in step (3) is 11,000 to 13,000 MPa·s, for example, 11,000 MPa·s, 11,500 MPa·s, 12,000 MPa·s, 12,500 MPa·s or 13,000 MPa·s, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0048] Maintaining the stability of the slurry viscosity can ensure the consistency of thickness during the coating process. Too high viscosity will lead to uneven surface tension and thickness of the coated electrode, and it will be more likely to form particles that clog the coating die, causing scratches on the electrode and affecting the later performance of the battery cell; if the viscosity of the slurry is too low, normal coating cannot be achieved, and it is difficult to form a uniform and stable coating.

[0049] In some embodiments, the solid content of the positive electrode slurry in step (3) is 65-66%, wherein the solid content can be 65%, 65.1%, 65.2%, 65.3%, 65.4%, 65.5%, 65.6%, 65.7%, 65.8%, 65.9% or 66%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0050] In some embodiments, based on the mass fraction of the positive electrode slurry being 100%, 95-96% lithium iron phosphate, 1-3% lithium supplement, 0.1-0.6% first conductive agent, 0.2-0.8% binder, 0.1-0.5% dispersant, 0.2-0.7% second conductive agent, and solvent are mixed to prepare a mixture with a solid content of 71-72%.

[0051] The process for replenishing lithium in the lithium iron phosphate cathode comprises:

[0052] (1) Mixing lithium iron phosphate and lithium supplement agent, performing a first stirring to obtain a main powder;

[0053] (2) mixing the first conductive agent, the binder, the dispersant, the solvent and the obtained main powder, and performing a second stirring to obtain the mixture having a viscosity of 12000 to 14000 MPa·s;

[0054] (3) The second conductive agent and the obtained mixture are mixed and stirred for the third time to obtain a positive electrode slurry with a viscosity of 11000-13000 MPa·s, thereby completing the lithium iron phosphate positive electrode lithium replenishment process.

[0055] According to another aspect of the present application, a positive electrode slurry is provided, and the positive electrode slurry is obtained using the process method.

[0056] According to another aspect of the present application, a positive electrode sheet is provided, wherein the positive electrode sheet contains the positive electrode slurry.

[0057] According to another aspect of the present application, a battery is provided, wherein the battery contains the positive electrode sheet.

[0058] Example 1

[0059] This embodiment provides a process for replenishing lithium in a lithium iron phosphate positive electrode. Taking the mass fraction of the positive electrode slurry as 100%, 95.2% lithium iron phosphate, 2% Li5FeO4, 0.4% conductive carbon black, 0.5% polyvinylidene fluoride, 0.2% polyvinyl pyrrolidone, 0.5% carbon nanotubes, and 1.2% N-methylpyrrolidone are taken;

[0060] The process comprises:

[0061] (1) Mix lithium iron phosphate and Li5FeO4 and perform a first stirring to obtain a main powder;

[0062] (2) mixing conductive carbon black, polyvinylidene fluoride, polyvinyl pyrrolidone, N-methyl pyrrolidone and the obtained main powder, and performing a second stirring to obtain the mixture having a viscosity of 13000 MPa·s;

[0063] (3) The carbon nanotubes and the obtained mixture are mixed and stirred for the third time to obtain a positive electrode slurry with a viscosity of 12000 MPa·s, thereby completing the lithium iron phosphate positive electrode lithium replenishment process.

[0064] Example 2

[0065] This embodiment provides a process for replenishing lithium in a lithium iron phosphate positive electrode. Taking the mass fraction of the positive electrode slurry as 100%, 95% lithium iron phosphate, 3% Li5FeO4, 0.1% conductive carbon black, 0.8% polyvinylidene fluoride, 0.1% polyvinyl pyrrolidone, 0.7% carbon nanotubes, and 0.3% N-methylpyrrolidone are taken;

[0066] The process comprises:

[0067] (1) Mix lithium iron phosphate and Li5FeO4 and perform a first stirring to obtain a main powder;

[0068] (2) mixing conductive carbon black, polyvinylidene fluoride, polyvinyl pyrrolidone, N-methyl pyrrolidone and the obtained main powder, and performing a second stirring to obtain the mixture having a viscosity of 12000 MPa·s;

[0069] (3) The carbon nanotubes and the obtained mixture are mixed and stirred for the third time to obtain a positive electrode slurry with a viscosity of 11000 MPa·s, thereby completing the lithium iron phosphate positive electrode lithium replenishment process.

[0070] Example 3

[0071] This embodiment provides a process for replenishing lithium in a lithium iron phosphate positive electrode. Taking the mass fraction of the positive electrode slurry as 100%, 96% lithium iron phosphate, 2% Li5FeO4, 0.6% conductive carbon black, 0.2% polyvinylidene fluoride, 0.5% polyvinyl pyrrolidone, 0.2% carbon nanotubes, and 0.5% N-methyl pyrrolidone are taken;

[0072] The process comprises:

[0073] (1) Mix lithium iron phosphate and Li5FeO4 and perform a first stirring to obtain a main powder;

[0074] (2) mixing conductive carbon black, polyvinylidene fluoride, polyvinyl pyrrolidone, N-methyl pyrrolidone and the obtained main powder, and performing a second stirring to obtain the mixture having a viscosity of 14000 MPa·s;

[0075] (3) The carbon nanotubes and the obtained mixture are mixed and stirred for the third time to obtain a positive electrode slurry with a viscosity of 13000 MPa·s, thereby completing the lithium iron phosphate positive electrode lithium replenishment process.

[0076] Example 4

[0077] This embodiment provides a process for replenishing lithium in a lithium iron phosphate positive electrode. The difference from Example 1 is that the viscosity of the mixture in step (2) is 11000 MPa·s.

[0078] Example 5

[0079] This embodiment provides a process for replenishing lithium in a lithium iron phosphate cathode, which differs from embodiment 1 in that

[0080] The viscosity of the mixture in step (2) is 15000 MPa·s.

[0081] Example 6

[0082] This embodiment provides a process for replenishing lithium in a lithium iron phosphate cathode, which differs from embodiment 1 in that

[0083] The viscosity of the positive electrode slurry in step (3) is 10000 MPa·s.

[0084] Example 7

[0085] This embodiment provides a process for replenishing lithium in a lithium iron phosphate positive electrode. The difference from Example 1 is that the viscosity of the positive electrode slurry in step (3) is 14000 MPa·s.

[0086] Comparative Example 1

[0087] This comparative example provides a process for replenishing lithium in a lithium iron phosphate positive electrode, which differs from Example 1 in that:

[0088] The lithium supplement is not mixed in step (1) but is mixed in step (2).

[0089] Comparative Example 2

[0090] This comparative example provides a process for replenishing lithium in a lithium iron phosphate positive electrode, which differs from Example 1 in that:

[0091] The lithium supplement is not mixed in step (1) but is mixed in step (3).

[0092] The cathode slurry obtained above was assembled into a lithium iron phosphate battery according to the process of baking, rolling, die cutting, winding and hot pressing, and tested. The test method was to weigh the pole pieces and measure the thickness with laser. The test results are shown in Table 1.

[0093] Table 1

[0094] Test No. Electrode Surface Density (g / ㎡) Electrode Thickness after Cold Pressing (mm) Example 1 192 169.3 Example 2 193 169.5 Example 3 192 169.8 Example 4 191 169.0 Example 5 193 169.6 Example 6 191 169.4 Example 7 191 169.9 Comparative Example 1 193 172 Comparative Example 2 194 173

[0095] In the first step, the present application mixes the positive electrode lithium supplement and lithium iron phosphate material into a main powder, so that the lithium supplement is fully uniform in the main powder system, and then the main powder is mixed with the remaining materials to form a positive electrode slurry, thereby ensuring the stability of the output, solving the problem of rapid viscosity increase during the slurry preparation process, and improving the performance of the battery cell.

[0096] From the comparison between Example 1 and Examples 4-5, it can be seen that if the viscosity of the mixture is too low, the surface density of the electrode decreases after cold pressing, and if the viscosity of the mixture is too high, the thickness of the electrode increases after cold pressing.

[0097] From the comparison between Example 1 and Examples 6-7, it can be seen that if the viscosity of the positive electrode slurry is too high or too low, the thickness of the electrode sheet increases after cold pressing, and the electrode sheet surface density of the battery decreases.

[0098] Comparison between Example 1 and Comparative Example 1 shows that the lithium supplement agent is not mixed in step (1) but is mixed in step (2), resulting in excessive electrode surface density, thick cold pressing thickness, and uneven dispersion.

[0099] Comparison between Example 1 and Comparative Example 2 shows that the lithium supplement agent is not mixed in step (1) but is mixed in step (2), resulting in excessive electrode surface density, thick cold pressing thickness, and uneven dispersion.

Claims

1. A process for replenishing lithium in a lithium iron phosphate positive electrode, the process comprising the following steps: Mixing lithium iron phosphate and a lithium supplement agent, performing a first stirring, and obtaining a main powder; Mixing the first conductive agent, the binder, the dispersant, the solvent and the obtained main powder, and performing a second stirring to obtain the mixed material; The second conductive agent and the obtained mixed material are mixed, and a third stirring is performed to obtain a positive electrode slurry, thereby completing the process method for replenishing lithium iron phosphate positive electrode lithium.

2. The process for replenishing lithium of lithium iron phosphate positive electrode according to claim 1, wherein: Preferably, the lithium supplement comprises Li5FeO4.

3. The process for replenishing lithium in a lithium iron phosphate positive electrode according to claim 1, wherein: Preferably, the mass of the lithium iron phosphate is 95-96% of the mass of the positive electrode slurry; Preferably, the mass of the lithium supplement is 1-3% of the mass of the positive electrode slurry.

4. The process for replenishing lithium in a lithium iron phosphate positive electrode according to claim 1, wherein: Preferably, the revolution speed of the first stirring is 15-25 r / min; Preferably, the first stirring dispersion speed is 180-220 r / min; Preferably, the first stirring time is 10 to 30 minutes.

5. The process for replenishing lithium in a lithium iron phosphate positive electrode according to claim 1, wherein: The mass of the first conductive agent is 0.1-0.6% of the mass of the positive electrode slurry.

6. The process for replenishing lithium in a lithium iron phosphate positive electrode according to claim 1, wherein: Preferably, the first conductive agent includes conductive carbon black.

7. The process for replenishing lithium in a lithium iron phosphate positive electrode according to claim 1, wherein: Preferably, the solvent comprises N-methylpyrrolidone.

8. The process for replenishing lithium in a lithium iron phosphate positive electrode according to claim 1, wherein: The binder includes polyvinylidene fluoride.

9. The process for replenishing lithium in a lithium iron phosphate positive electrode according to claim 1, wherein: Preferably, the dispersant comprises polyvinyl pyrrolidone.

10. The process for replenishing lithium in a lithium iron phosphate positive electrode according to claim 1, wherein: Preferably, the mass of the binder is 0.2-0.8% of the mass of the positive electrode slurry; Preferably, the mass of the dispersant is 0.1-0.5% of the mass of the positive electrode slurry.

11. The process for replenishing lithium in a lithium iron phosphate positive electrode according to claim 1, wherein: Preferably, the second stirring revolution speed is 10-20 r / min; Preferably, the second stirring dispersion speed is 180-220 r / min; Preferably, the second stirring time is 5 to 15 minutes.

12. The process for replenishing lithium of a lithium iron phosphate positive electrode according to any one of claims 1 to 11, wherein: The second conductive agent includes carbon nanotubes.

13. The process for replenishing lithium in a lithium iron phosphate positive electrode according to claim 12, wherein: Preferably, the mass of the second conductive agent is 0.2-0.7% of the mass of the positive electrode slurry.

14. The process for replenishing lithium in a lithium iron phosphate positive electrode according to claim 12, wherein: Preferably, the revolution speed of the third stirring is 15-25 r / min; Preferably, the third stirring time is 100-140 min.

15. The process for replenishing lithium in a lithium iron phosphate positive electrode according to claim 12, wherein: The viscosity of the mixture is 12000~14000MPa·s; Preferably, the viscosity of the positive electrode slurry is 11000-13000 MPa·s.

16. The process for replenishing lithium in a lithium iron phosphate positive electrode according to claim 12, wherein: Preferably, the solid content of the mixture is 71-72%.

17. The process for replenishing lithium in a lithium iron phosphate positive electrode according to claim 12, wherein: Preferably, the positive electrode slurry has a solid content of 65-66%.

18. The process for replenishing lithium in a lithium iron phosphate positive electrode according to any one of claims 1 to 17, the process comprising: Mixing lithium iron phosphate and a lithium supplement agent, performing a first stirring, and obtaining a main powder; Mixing the first conductive agent, the binder, the dispersant, the solvent and the obtained main powder, and performing a second stirring to obtain a mixture with a viscosity of 12000-14000 MPa·s; The second conductive agent and the obtained mixture are mixed, and a third stirring is performed to obtain a positive electrode slurry with a viscosity of 11000-13000 MPa·s, thereby completing the process method for replenishing lithium iron phosphate positive electrode lithium.

19. A positive electrode slurry, wherein the positive electrode slurry is obtained by the process according to any one of claims 1 to 18.

20. A battery comprising the positive electrode slurry according to claim 19.

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